Tracker Estimates

The tracker range is the distance from the satellite to the Earth's surface corrected for instrumental corrections such as USO frequency drift, internal path correction or Doppler correction.

The geophysical corrections are not applied to the tracker range. The AGC (Automatic Gain Control) is the gain applied on-board to the waveforms and corrected for instrumental errors.

The sigma0 scaling factor is used to compute the backscatter coefficient of the waveforms. The sigma0 scaling factor represents a backscatter coefficient for waveform amplitude equal to 1.


 

PARAMETER

AGC Corrected Estimate

NETCDF NAME

agc_[x1]_[x2] where
[x1]: 1 Hz or 20 Hz data rates
[x2]: Ku-band or C-band.

DESCRIPTION

AGC corrected for instrumental errors (agc_cor_[x1]_[x2])For SAR mode, the correction value is the closest in time to the reference measurement.

UNITS

10-2 dB

DATA SET AVAILABILITY

Reduced: none
Standard: 1 Hz only
Enhanced: all

OPERATING MODE AVAILABILITY

LRM and SAR

DATA ORIGIN

 1 Hz Ku/C-bands: ALT_COM_AGC_01 algorithm
20 Hz Ku-band: SRAL Level-1B product
20 Hz C-band: SRAL Level-1B product

ADDITIONAL INFORMATION

 None

PARAMETERS RELATED

Number of valid points to compute AGC (agc_num_val_[x1]_[x2])
RMS of the AGC (agc_rms_[x1]_[x2])
AGC validity flag (agc_qual_[x1]_[x2]). Flag indicating the use or not of the 20 Hz estimate of AGC in the computation of 1 Hz estimate.

PARAMETER DETAILED DESCRIPTION

ESA's Global Land and Ocean Mission for GMES Operational Services

Table 1. AGC

 

 

PARAMETER

Scaling Factor for Sigma0 Evaluation

NETCDF NAME

scale_factor_[x1]_[x2]
[x1]: 1 Hz or 20 Hz data rates
[x2]: Ku-band or C-band

DESCRIPTION

Scaling factor for backscatter coefficient (sigma0) evaluation. This scaling factor represents the backscatter coefficient for waveform amplitude equal to 1. It is corrected for:
*AGC instrumental errors (agc_cor_[x1]_[x2])
*Internal calibration (sig0_cal_[x1]_[x2])

UNITS

10-2 dB

DATA SET AVAILABILITY

Reduced: none
Standard: none
Enhanced: 20 Hz Ku and 20 Hz C-band only

OPERATING MODE AVAILABILITY

LRM and SAR

DATA ORIGIN

1 Hz Ku/C-bands: none
20 Hz Ku-band: SRAL Level-1B product
20 Hz C-band: SRAL Level-1B product

ADDITIONAL INFORMATION

 None

PARAMETERS RELATED

None

PARAMETER DETAILED DESCRIPTION

ESA's Global Land and Ocean Mission for GMES Operational Services

Table 2. Sigma0 scaling factor

 
 

PARAMETER

Tracker Range Estimate

NETCDF NAME

tracker_range_[x1]_[x2]
[x1]: 1 Hz or 20 Hz data rates[x2]: Ku-band or C-band

DESCRIPTION

LRM mode: tracker range corrected for: USO frequency drift (uso_cor_[x1]_[x2]), internal path correction (int_path_cor_[x1]_[x2]), Doppler correction (dop_cor_l1b_[x1]_[x2])
SAR mode : reference range corrected for: USO frequency drift (uso_cor_[x1]_[x2]), internal path correction (int_path_cor_[x1]_[x2])

UNITS

10-4 m. An offset of 700 000 m to be added to the value read from the netCDF file.

DATA SET AVAILABILITY

Reduced: none
Standard: none
Enhanced: 20 Hz Ku and C-bands

OPERATING MODE AVAILABILITY

LRM and SAR

DATA ORIGIN

1 Hz Ku/C-bands: none
20 Hz Ku-band: SRAL Level-1B product
20 Hz C-band: SRAL Level-1B product

ADDITIONAL INFORMATION

 None

PARAMETERS RELATED

Altitude on-board command (H0) computed with navigation/digital elevation model(h0_nav_dem_[x1]_[x2]). Units are on-board clock counter units (3.125/64x10-9 seconds).
This parameter is only available in the enhanced 20 Hz - Ku-band data set.

PARAMETER DETAILED DESCRIPTION

ESA's Global Land and Ocean Mission for GMES Operational Services

Table 3. Tracker range